1. Field of the Invention
The present invention relates to a road surface layer reproducing apparatus and, more particularly, to a road surface layer reproducing apparatus which is adapted to reproduce for remedy the upper surface of a road paved with asphalt while it is being caused to travel.
2. Description of the Prior Art
Conventionally, a road surface which is paved with asphalt was generally reproduced for remedy through execution of the following steps. First of all, the paved road surface is heated. Then, it is scarified to a depth by means of a scarifier, and a softening agent is scattered on the road surface layer thus scarified. Thereafter, the resulting road surface layer is stirred by means of rotors, at which time a new asphalt mixture is added as the necessity arises. The road surface layer, thereafter, is spread and levelled by screw spreaders and then is tamped by screeds, followed by a final step in which the resulting surface is rolled. Of these reproducing steps, the heating step and the rolling step are carried out by an automotive road-surface heater vehicle and a road roller, respectively, while, on the other hand, the intermediate steps are carried out by use of various devices concerned which are incorporated in a road surface layer reproducing apparatus involved. This road surface layer reproducing apparatus is in the form of an automotive vehicle and generally is constructed such that at a lower part of the automotive vehicle, a new mixture hooper, a scarifier, a rotor, a screw spreader and a screed are disposed sequentially in that order from a front side of the vehicle so as to serve their respective use purposes.
However, the above-mentioned prior art road surface layer reproducing apparatus has the following problems.
(1) The hopper has an opening at its underside, beneath which is disposed a bar feeder so as to convey a mixture received therein to a rearward position of the vehicle body, a frontward part of the hopper being able to be vertically swung about a base end portion of a hopper-supporting arm. In the prior art apparatus, however, the pieces of the mixture which have attached onto side walls of the hopper can not automatically be caused to drop but are manually scratched down. Thus, an unnecessary labour is required to be used for such purpose. In addition, an asphalt mixture often fails to be equally carried rearwardly of the vehicle.
(2) Although the scarifier can be vertically raised and lowered as a whole, its claws can not be vertically moved for each block in such a manner as to follow up the surface of a road involved. As a result, where the road surface is not flat but has convexities and concavities (which are created as a result of, for example, rutting), the apparatus fails to scarify the road surface to a uniform depth.
(3) Since the rotor is of single-shaft type, it fails to sufficiently stir the scarified surface layer when the scarified depth is large. This makes it difficult to effect a homogeneous reproduction of the surface layer.
(4) Further, a certain old type of road surface layer reproducing apparatus has a rotor system wherein mixing is effected with the use of two-shaft rotors (connceted vertically in series) in the advancing direction of the vehicle. However, where the reproduction depth is small, such vertical type of mixer fails to provide a sufficiently high mixability on account of deficiency in quantity of the materials to be mixed. Conversely, where the reproduction depth is large, the mixer fails to process the full reproduction depth because of excess in quantity of such materials. Further, the surface of the scarified layer is exposed, at both end portions of the vehicle, to the open air and in consequence is cooled. This obstructs the adherence of the reproduction layer to a previous pavement located under the same. This becomes a cause of exfoliation of the former from the latter.